Vehicle door

ABSTRACT

A vehicle door ( 10 ) includes an inner door panel ( 11 ). The inner door panel includes a door frame ( 20 ) and elongated members ( 25, 26 ). The elongated members extend in a front-and-rear direction of a vehicle body. The elongated members have fragile sections ( 60 ) each extending in a widthwise direction of the vehicle body to provide a stepped portion. The fragile section fractures under the action of a fracturing stress produced when a compression force (FO) greater than predetermined intensity acts on the elongated members. One element of the elongated member having the thus fractured fragile section then moves to absorb the compression force, thereby enhancing a passenger protecting performance of the vehicle door.

TECHNICAL FIELD

The present invention relates to a technique for improving performanceof a door to protect a passenger or driver (hereinafter, genericallyreferred to as a passenger) in a motor vehicle.

BACKGROUND ART

In recent years, techniques have been developed for protecting apassenger of a vehicle from a collision force acting on the vehicle. Forenhanced passenger protecting performance, there has been a demand forreconsideration of the overall vehicle body structure including doors.As an example of a vehicle door designed to enhance the passengerprotecting performance, there is known a “vehicle door structure”disclosed in Japanese Patent Laid-open Publication No. HEI-7-25236.

The disclosed vehicle door structure includes an opening portion in anupper area of a door body composed of inner and outer panels, and awindow panel is provided in the opening portion for up-and-down movementthrough the opening.

To secure necessary structural rigidity of the opening portion,reinforcements are provided respectively in an upper portion of theinner panel and upper inner portion of the outer panel and extend alongthe opening portion. Each of these reinforcements has a recessed portionformed therein to be located forwardly of a hip point of the passenger.When an external force has acted on the door body from sideways of thevehicle, namely, a certain object has collided with a side door of thevehicle, the reinforcements deform plastically, at the position of therecessed portions, toward the interior of a vehicle compartment, so thatthe collision energy can be absorbed by the plastic deformation of thereinforcements. Thus, a collision impact applied to the passenger can bealleviated, which thereby enhances the passenger protecting performanceof the vehicle door.

For the aforementioned vehicle door having the reinforcements designedto deform plastically towards the interior of the vehicle compartmentwhen the external force acts on the vehicle door from sideways, however,the reinforcements are not designed allowing for occurrence of impact orcollision on a front part of the vehicle. In other words, no measure istaken against application of an external force to the vehicle from afront side of the vehicle. There has been needed a vehicle door designedto ensure the enhanced passenger protecting performance even when thevehicle is subjected to the external force from the front side thereof.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention, there is provided avehicle door including an inner door panel and being attachable to avehicle body, the inner door panel comprising: a door frame; elongatedmembers extending in a front-and-rear direction of the vehicle bodywithin the door frame; the elongated members each including: a pair ofelements extending in the front-and-rear direction of the vehicle body;fragile sections each extending, in a widthwise direction of the vehiclebody, between the pair of elements to provide a stepped portion; and thefragile section being designed to be fractured by a fracturing stresswhen a compression force greater than predetermined intensity acts onthe elongated members.

When collision force acts on the door from ahead of the vehicle body,the fragile section which provides a stepped portion is fractured underthe action of a fracturing stress. Fracturing of the fragile sectioncauses one of the pair of elements extending in the front-and-reardirection of the vehicle body to move rearward to absorb collisionenergy. Use of the inner door panel makes it possible to promptly reduceor absorb enough of the collision energy from ahead of the vehicle. Inaddition, by setting, as appropriate, the locations of the fragilesections on the elongated members, it is possible to clearly identifypositions where fracture occurs when a collision force acts on the doorfrom ahead of the vehicle body. Therefore, it suffices to just setappropriate locations of the fragile sections such that the passengerprotecting performance can be enhanced.

Preferably, the elongated member has the fragile sections provided at afront or rear part thereof, and has a longitudinally-middle portionthereof located farther from a vehicle compartment of the vehicle bodythan the front or rear part. This means that, of the elongated members,the shorter element extending from the high-rigidity door frame to thestepped portion is disposed closer to the interior of the vehiclecompartment. Thus, the shorter element has greater rigidity than thelonger element. Therefore, in case the stepped portion fractures, it ispossible to minimize adverse influences on the interior of the vehiclecompartment.

Preferably, the inner door panel is formed by casting. It is easier toset a shape and size of the stepped portion of the fragile section,i.e., shapes and sizes of the pair of elements extending in thefront-and-rear direction of the vehicle body and of the stepped portionextending in the widthwise direction of the vehicle body, and therebyset the fracturing portion with higher accuracy, than in a case wherethe inner door panel is press-formed.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the present invention will be describedin detail below, by way of example only, with reference to theaccompanying drawings, in which:

FIG. 1 is a side view of a vehicle door in accordance with an embodimentof the present invention;

FIG. 2 is a side view showing a lower half of an inner door panel of thevehicle door of the present invention;

FIG. 3 is a sectional view taken along line 3—3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4—4 of FIG. 2;

FIG. 5 is a sectional view taken along line 5—5 of FIG. 2;

FIG. 6A is a sectional plan view of first and second elongated membershaving fragile sections, and FIG. 6B is a view showing one of the firstand second elongated members having fractured in the fragile section;

FIG. 7 is a sectional view taken along the 7—7 line of FIG. 2; and

FIG. 8A is a schematic side view of the vehicle door having a door beam,FIG. 8B is a view showing a state of the vehicle door at a moment when acollision force has acted on the door beam, and FIG. 8C is a viewshowing a state of the vehicle door immediately after the collisionforce has acted on the door beam and a first dividing element has movedrearward relative to a second dividing element.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a structure of a left front door 10 of a full-door typevehicle as viewed from a left side of the door 10. The door 10 iscomposed of an inner door panel 11 having a window sash 12 formedintegrally with an upper end portion thereof, and an outer door panel 13joined with an outer side—i.e., a side facing a viewer of the figure—ofthe inner door panel 11. The door 10 is mounted for opening and closingmovement with a door frame 20 of the inner door panel 11 attached viaupper and lower hinges 32 to a vehicle body 31 denoted by a phantom linein the figure, and it is held in the closed position by means of a doorlock section 35 secured to the door frame 20.

The window sash 12 is a component holding therein a door glass (notshown) in such a manner that the glass can be raised and lowered alongthe sash 12. In this description, the terms “inner door panel”collectively refer to a combination of the panel 11 and window sash 12.

The door frame 20 of the inner door panel 11 includes a horizontal lowerframe member 21, a front frame member 22 extending upward from the frontend of the lower frame member 21, a rear frame member 23 extendingupward from the rear end of the lower frame member 21, and an upperframe member 24 extending between the respective top ends of the frontframe member 22 and rear frame member 23.

The inner door panel 11 is formed of a magnesium alloy material with aview to reducing its weight; for example, the inner door panel 11 ismade by casting (preferably, die-casting) such a magnesium alloymaterial. This is because a magnesium alloy material has a low meltingpoint and presents a good fluid flow capability. For example, amagnesium alloy diecasting of Type B (JIS H5303, MD2B) is preferable.

The outer door panel 13 is made by press-forming a sheet-shapedmaterial, such as a magnesium alloy sheet, aluminum alloy sheet or steelsheet.

Further, in FIG. 1, there is also shown a relationship between the door10 and a seat 40 for a passenger Ma (i.e., driver's or passenger'sseat). The passenger seat 40, denoted by a phantom line in the figure,includes a seat cushion 41 and a seat back 42. The seat cushion 41 isdisposed near a rear lower portion of the door frame 20, while the seatback 42 is disposed near a rear portion of the door frame 20.

The door frame 20 includes a first elongated member 25 extendingsubstantially horizontally and facing a side surface of the seat back 42retained in an upright position. Thus, the first elongated member 25substantially faces a shoulder Sh of the passenger Ma. The firstelongated member 25 is a reinforcing member extending between the topend of the front frame member 22 and a height-wise middle portion of therear frame member 23.

FIG. 2 shows a lower half of the inner door panel 11, which includes thedoor frame 20 and a plurality of elongated members (the above-mentionedfirst elongated member 25 and a second elongated member 26) extending inthe front-and-rear direction of the vehicle body within the door frame20. Specifically, the first elongated member 25 and second elongatedmember 26 are elongated door beams formed integrally with the door frame20. The second elongated member 26 extends from a front lower portion(i.e., a corner between the lower frame member 21 and the front framemember 22) of the door frame 20 obliquely toward a rear end portion ofthe first elongated member 25.

The first elongated member 25 has one fragile section 60 at its frontend, and the second elongated member 26 has two fragile sections 60 atits front end and one fragile section 60 at its rear end. These fragilesections 60 are located at given distances from the passenger Ma seatedon the seat 40 shown in FIG. 1. Details of the fragile sections 60 willbe discussed later.

The front frame member 22 has the two hinges 32 secured to its upper andlower portions. The rear frame member 23 has the door lock section 35secured to a height-wise or vertically middle portion thereof thatcorresponds generally to a midpoint between the upper and lower hinges32 of the front frame member 22.

The door frame 20 includes a door beam 70 connected between the securedpositions of the upper hinge 32 and door lock section 35, and anotherdoor beam 70 connected between the secured positions of the lower hinge32 and door lock section 35.

FIG. 3 is a sectional plan view of the rear frame member 23 and firstelongated member 25. The first elongated member 25 has an inner wallsurface 25 a facing the interior of a vehicle compartment In and apassenger protecting cover 51 secured to the surface 25 a in overlappedrelation thereto. The passenger protecting cover 51 is a press-formedsheet of a relatively lightweight aluminum alloy that has greatertoughness than the magnesium alloy used in the inner door panel 11. The“toughness” represents how tenacious and how difficult the material isto fracture or break due to an external impact.

Front end portion 51 a of the passenger protecting cover 51 is securedlocally to a front portion of the first elongated member 25 of the innerdoor panel 11 in overlapped relation by means of a plurality of rivets52. Rear end portion 51 b of the passenger protecting cover 51 issecured locally to a bracket 53, along with the first elongated member25, in overlapped relation to the bracket 53, by means of a plurality ofrivets 54. The bracket 53 is secured locally to the rear frame member 23of the door frame 20 by means of a plurality of rivets 55.

FIG. 4 shows in detail how the front end portion 51 a of the passengerprotecting cover 51 is secured to the first elongated member 25 inoverlapped relation by means of the plurality of rivets 52.

FIG. 4 also shows a door glass 58 accommodated in an opening 57 betweenthe first elongated member 25 and the outer door panel 13 forclosing/opening vertical movement through the opening 57.

FIG. 5 shows in detail how the rear end portion 51 b of the passengerprotecting cover 51 is secured to the bracket 53, together with thefirst elongated member 25, in overlapped relation to the bracket 53, bymeans of the plurality of rivets 54.

Referring back to FIG. 1, because the first elongated member 25 facesthe seat 40, the passenger protecting cover 51 is also positioned in aportion of the inner door panel 11 which faces at least the seat 40 orvicinity thereof. Further, the inner door panel 11 and passengerprotecting cover 51 are secured together to the bracket 53 in overlappedrelation thereto in the portion facing the seat 40 or vicinity thereof.

FIGS. 6A and 6B show sections of the first and second elongated members25 and 26, and FIG. 6B particularly shows the fragile section 60 in afractured state.

The fragile section 60 is a portion that is designed to be fractured bya fracturing stress when a compression force greater than predeterminedintensity acts on the first and second elongated members 25 and 26 in alongitudinal direction thereof. The fragile section 60 is formedintegrally with the first and second elongated members 25 and 26.

Specifically, each of the fragile sections 60 is a stepped portionformed by a short connecting portion (fracturing portion) 63 extending,in the widthwise direction of the vehicle body, between a pair of firstand second elements 61 and 62 extending generally serially in thefront-and-rear direction of the vehicle body. The second element 62, asa longitudinally-middle portion of each of the first and secondelongated members 25 and 26, is located closer to the outside Ou of thevehicle (farther from the vehicle compartment) than the first element61. Respective wall thicknesses t1, t2 and t3 of the first element 61,second element 62 and fracturing portion 63 are generally identical toeach other.

Behavior of each of the fragile sections 60 will now be described withreference to FIGS. 6A and 6B. The fracturing portion 63 can fracturewhen a compression force greater than predetermined intensity acts onthe first and second elongated members 25 and 26 in the longitudinaldirection thereof as seen in FIG. 6A. Namely, when a collision force Foacts on the inner door panel 11 from ahead of the vehicle body, thefracturing portion 63 fractures due to the collision force Fo. As aconsequence, the first element 61 moves rearward relative to the secondelement 62 as illustrated in FIG. 6B, so that the collision energy fromahead of the vehicle body can be absorbed and lessened by the inner doorpanel 11 promptly and even more effectively.

In addition, by setting, as appropriate, the locations of the fragilesections 60 on the first and second elongated members 25 and 26, it ispossible to clearly identify positions where fracture occurs when acollision force acts on the door 10 from ahead of the vehicle body.Therefore, it suffices to just set appropriate locations of the fragilesections 60 such that the passenger protecting performance can beenhanced.

With such arrangements, the instant embodiment can enhance the passengerprotecting performance of the vehicle door 10 against a collision forceFo imparted from ahead of the vehicle body.

Further, the door frame 20 has relatively great rigidity. Of the firstand second elongated members 25 and 26, the shorter element (firstelement 61) extending from the high-rigidity door frame 20 to thestepped portion is disposed closer to the interior of the vehiclecompartment In. Thus, the shorter element has greater rigidity than thelonger element (second element 62). Therefore, in case the steppedportion fractures, it is possible to minimize adverse influences on theinterior of the vehicle compartment In.

Moreover, in the instant embodiment where the inner door panel 11 isformed by casting, it is easier to set a shape and size of the steppedportion of the fragile section 60, i.e. shapes and sizes of the pair ofelements (first and second elements 61 and 62) extending in thefront-and-rear direction of the vehicle body and of the shorter element(fracturing portion 63) extending in the widthwise direction of thevehicle body, and thereby set the fracturing portion with higheraccuracy, than in a case where the inner door panel 11 is press-formed.

FIG. 7 shows a sectional structure of the door beam 70 referred toearlier in relation to FIG. 2. The door beam 70 in the instantembodiment includes a series of dividing members (first and seconddividing members 71 and 72), which have their respective end portions 71b and 72 a overlapped with each other in the widthwise direction of thevehicle body and joined with each other in such a manner that thedividing members are movable relative to each other by a predetermineddistance when a compression force greater than predetermined intensityacts on the door beam 70.

Specifically, in the illustrated example, the dividing members includethe first dividing member 71 positioned closer to the hinge 32 andsecond dividing member 72 positioned closer to the door lock section 35,and the mutually-joined areas of the end portions 71 b and 72 a arelocated near the hinge 32. The first dividing member 71 is locatedcloser to the interior of the vehicle compartment In than the seconddividing member 72.

One element of the hinge 32 is fixed, via a bolt and nut fastener 33, tothe vehicle body 31 denoted by a phantom line, while the other elementof the hinge 32 is fixed, via a bolt 73, to the front frame member 22along with a front end portion 71 a of the first dividing member 71. Thefront end portion 72 a of the second dividing member 72 is overlappedover the rear end portion 71 b of the first dividing member 71 in thewidthwise direction of the vehicle body and joined, via a bolt 74, withthe rear end portion 71 b of the first dividing member 71. Further, arear end portion 72 b of the second dividing member 72 and a bracket 36of the door lock section 35 are overlapped with each other in thewidthwise direction of the vehicle body and joined with each other by arivet 75. The bracket 36 and rear frame member 23 are coupled with eachother by a rivet 76 and bolt and nut fastener 77.

The rear end portion 71 b of the first dividing member 71 is locatedcloser to the interior of the vehicle compartment In than the front endportion 72 a of the second dividing member 72.

The door lock section 35 comprises a conventional mechanism including alatch member (not shown) that is fixed to the bracket 36 and engages astriker (not shown) fixed to the vehicle body 31. The bracket 36 andfirst and second dividing members 71 and 72 are each a press-formedsheet of an aluminum alloy material.

More specifically, the corresponding end portions 71 b and 72 a of thefirst and second dividing members 71 and 72 are joined with each otherin either of two manners to be explained in (1) and (2) below.

(1) Round hole 78 is formed in the rear end portion 71 b of the firstdividing member 71 to extend there through in the widthwise direction ofthe vehicle body, and a hole 79, elongated in the longitudinal directionof the door beam 70, is formed in the front end portion 72 a of thesecond dividing member 72 to extend there through in the widthwisedirection of the vehicle body. Then, the end portions 71 b and 72 a arecoupled with each other by the bolt 74 extending through the round hole78 and elongated hole 79.

(2) Hole 79, elongated in the longitudinal direction of the door beam70, is formed in the rear end portion 71 b of the first dividing member71 to extend therethrough in the widthwise direction of the vehiclebody, a round hole 78 is formed in the front end portion 72 a of thesecond dividing member 72 to extend therethrough in the widthwisedirection of the vehicle body, and the end portions 71 b and 72 a arejoined together via the bolt 74.

The elongated hole 79 has a length L1, which determines a range overwhich the first and second dividing elements 71 and 72 are movablerelative to each other.

FIG. 8A is a schematic side view of the door 10, FIG. 8B shows a stateof the vehicle door when a collision force Fo has acted on the door beam70, and FIG. 8C shows a state of the vehicle door immediately after thecollision force Fo has acted on the door beam 70.

In FIGS. 8A and 8B, when a compressing force greater than predeterminedintensity has acted on the door beam 70 in the longitudinal directionthereof, the compressing force exceeds friction occurring between theend portions 71 b and 72 a through the tightening by the bolt 74. As aconsequence, the first and second dividing elements 71 and 72 can moverelative to each other.

When the collision force FO acts on the door beam 70 by way of the hinge32 from ahead of the vehicle body, the collision force Fo is transmittedfrom the first element 71, via the round hole 78, to the bolt 74. Oncethe collision force Fo exceeds the friction between the end portions 71b and 72 a, the first dividing element 71 moves rearward relative to thesecond dividing element 72 as illustrated in FIG. 8C. Note that adistance L2 over which the first and second dividing elements 71 and 72can move relative to each other depends on the length L1 (see FIG. 7) ofthe elongated hole 79. In the above-described manner, the collisionenergy can be absorbed.

It should be appreciated that the vehicle door 10 embodying basicprinciples of the present invention is not limited to the left frontdoor and may be the right front door, left rear door or right rear door.

Further, the vehicle door 10 embodying the present invention is notlimited to the full door type; for example, it may be a sash-equippeddoor having a separate sash body secured to an upper portion of theinner door panel or a sash-less door.

Furthermore, the inner door panel 11 in the present invention is notlimited to one made of a magnesium alloy material; for example, it maybe made of an aluminum alloy or steel. Moreover, the inner door panel 11may be made by press-forming rather than by casting.

Moreover, the passenger protecting cover 51 may be made of any othersuitable material than a nonferrous material like an aluminum alloy,such steel, hard rubber or engineering plastics, as long as the materialof the protecting cover 51 has greater “toughness” than the inner doorpanel 11.

In addition, the arrangement for fixing the passenger protecting cover51 to the inner door panel 11 may be chosen as appropriate taking thematerial of the cover 51 into consideration; for example, the passengerprotecting cover 51 may be fixed to the inner door panel 11 by bolts,spot-welding rather than by rivets.

INDUSTRIAL APLICABILITY

According to the present invention, when the collision force acts on theinner door panel from ahead of the vehicle body, the fragile section(s)each providing a stepped portion formed on the elongated member of theinner door panel fracture under the action of fracturing stress. Oneelement of the elongated member then moves rearward to absorb collisionenergy. This becomes possible to enhance the passenger protectingperformance of the vehicle door. The thus arranged vehicle door isadvantageous and useful in applications to the automobile industry.

1. A vehicle door including an inner door panel and being attachable toa vehicle body, said inner door panel comprising: a door frame;elongated members extending in a front-and-rear direction of the vehiclebody within said door frame; said elongated members each including: apair of elements extending in the front-and-rear direction of thevehicle body; a fragile section extending, in a widthwise direction ofthe vehicle body, between the pair of elements to provide a steppedportion; and said fragile section being designed to be fractured by afracturing stress when a compression force greater than predeterminedintensity acts on the elongated members.
 2. A vehicle door according toclaim 1, wherein each of said elongated members has its respectivefragile section provided at a front or rear part thereof, and has alongitudinally-middle portion thereof located farther from a vehiclecompartment of the vehicle body than the front or rear part where thefragile section is provided.
 3. A vehicle door according to claim 1,wherein said inner door panel is formed by casting.